Data are presented which show that three distinct optical recombination transitions occur inp‐type GaAs:Si. These recombination transitions are band to band, conduction band to shallow acceptor, and conduction band to deep acceptor. With adequate pumping, as shown on ultrathin platelets, laser emission due to any of these transitions is possible, depending upon the cavity resonator gain profile and the crystal doping concentration. The effect of compensating Si donors in the crystal upon the wavelength of emission is illustrated. The unusually broad spontaneous linewidth ofp‐type GaAs:Si demonstrated here, along with the very large spatial spread of injected carriers in a GaAs:Si solution‐grownp‐njunction, is argued as being the limiting factors to stimulated emission in junction structures.